INFO: rcu detected stall in __bitmap_set

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
cb6416592bc2a8b731dabcec0d63cda270764fc6 (Sun Mar 25 17:45:10 2018 +0000)
Merge tag 'dmaengine-fix-4.16-rc7' of  
git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/slave-dma
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=c479aeac880b090ceeb2

So far this crash happened 3 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5205501092560896
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-5034017172441945317
compiler: gcc (GCC) 7.1.1 20170620

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Reported-by: syzbot+c479aeac880b090ceeb2@xxxxxxxxxxxxxxxxxxxxxxxxx
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

INFO: rcu_sched self-detected stall on CPU
	1-....: (124999 ticks this GP) idle=1ca/1/4611686018427387906  
softirq=17365/17365 fqs=31238
	 (t=125000 jiffies g=7965 c=7964 q=402)
NMI backtrace for cpu 1
CPU: 1 PID: 6633 Comm: syz-executor6 Not tainted 4.16.0-rc6+ #366
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x186/0x1de kernel/rcu/tree.c:1375
 print_cpu_stall kernel/rcu/tree.c:1524 [inline]
 check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1592
 __rcu_pending kernel/rcu/tree.c:3361 [inline]
 rcu_pending kernel/rcu/tree.c:3423 [inline]
 rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763
 update_process_times+0x30/0x60 kernel/time/timer.c:1636
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194
 __run_hrtimer kernel/time/hrtimer.c:1349 [inline]
 __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411
 hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:106
RSP: 0018:ffff8801ce8ef680 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff12
RAX: 0000000000010000 RBX: ffffffffffffff80 RCX: ffffffff825ae73d
RDX: 000000000000ffff RSI: ffffc90004a0d000 RDI: ffff8801d1a15660
RBP: ffff8801ce8ef680 R08: ffffed003a342acd R09: ffff8801d1a15660
R10: 0000000000000001 R11: ffffed003a342acc R12: ffffffffffffffff
R13: 0000000000000000 R14: ffff8801d1a15660 R15: 0000000000000000
 __bitmap_set+0xdd/0x110 lib/bitmap.c:274
 bitmap_set include/linux/bitmap.h:365 [inline]
 __bitmap_parselist+0x310/0x4b0 lib/bitmap.c:616
 bitmap_parselist+0x3a/0x50 lib/bitmap.c:628
 cpulist_parse include/linux/cpumask.h:639 [inline]
 update_cpumask kernel/cgroup/cpuset.c:974 [inline]
 cpuset_write_resmask+0x1694/0x2850 kernel/cgroup/cpuset.c:1724
 cgroup_file_write+0x2ae/0x710 kernel/cgroup/cgroup.c:3429
 kernfs_fop_write+0x2bc/0x440 fs/kernfs/file.c:316
 __vfs_write+0xef/0x970 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454879
RSP: 002b:00007fd0e0f38c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd0e0f396d4 RCX: 0000000000454879
RDX: 0000000000000008 RSI: 0000000020000080 RDI: 0000000000000015
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000067c R14: 00000000006fac40 R15: 0000000000000000


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